This invention relates to distribution of compressed video for video services and provides an efficient method to use improved compression technologies while taking advantage of already-installed infrastructure.
Video services are currently being distributed digitally in compressed form by a wide array of video content suppliers. For example, residential digital video services may include digital television, video-on-demand, Internet streaming video, and so forth. One widely used compressed video standard for use in video services is the Moving Picture Experts Group (MPEG) MPEG-2 standard. For example, many receivers for digital video programs, e.g., set-top boxes (STBs) located in residential homes, receive video programs in the MPEG-2 format from a number of different video content suppliers via assorted transmission channels.
A video program may start as an analog program and be encoded into an MPEG-2 standard based transport stream. Alternately, the program may already be stored in a library in MPEG-2 format. The compressed transport stream may then be sent to the home in a variety of transport mechanisms, including one or more satellite links, digital subscriber loop access links, optical network links, coaxial cable networks, ATM networks, IP-based networks, satellite networks, wireless networks, and terrestrial broadcast networks.
Many standards are known for compressing video. The Moving Picture Experts Group (MPEG) has adopted a set of standards for video compression, including MPEG-1, MPEG-2 and MPEG-4. The ITU (International Telecommunication Union) has also developed several standards: the H.261, H.263, H.263+, H.263++. While many of these standards are widely known and used, it is currently only MPEG-2 that has a large infrastructure in-place. MPEG-2 is widely used in consumer DVDs, for satellite and digital cable television broadcasts, for video on demand (VOD), and so forth.
While MPEG-2 is certainly in widespread use, continues to be deployed, and is likely to continue to be deployed for quite some time, there has been continued effort to develop compression technologies that improve on the amount of compression achievable to obtain a given reconstructed image/video quality. The ITU-T Video Coding Experts Group (VCEG) started working a proposed H.26L standard in 1997. In 2001, ISO/IEC MPEG joined the ITU-T VCEG to form a Joint Video Team (JVT) that took over the H.26L project of the ITU-T. The result of this effort is an emerging standard that dramatically improves the coding efficiency over that achievable with the now-common MPEG-2, even achieving more than 50% bit rate saving for the same picture quality. This standard is called H.264 herein. New techniques continue to be developed, and it will not be surprising if within a few years, a new compression method is available that provides yet another improvement in compression—as much as 50%.
Because MPEG-2 has been so widely adopted, with many billions of dollars already invested in infrastructure, e.g., in set top boxes that use MPEG-2, and because MPEG-2 provides “good enough” performance, and because MPEG-2 continues to be deployed, it would be difficult to convince entities that have invested heavily in MPEG-2 and other heavily adopted technology to abandon this investment to adopt the “latest and greatest” technology, even if such a new technology provides a significantly higher compression ratio. The inventors, who are experts in the field, expect MPEG-2 to continue to be used for many years.
Thus there is a need for methods and apparatuses that provide for using new improved compression methods in video distribution without forsaking investments already made in existing technology.
Note that it is only in the last few years that a digital video standard, MPEG-2, has started becoming so common. It is the first commonly used video standard. While previous standards were known and used, e.g., MPEG-1 and H.261, their use was relatively limited and their replacement using newer technology, such as MPEG-2, was without significant problems. Only now that there has been such widespread use of MPEG-2 is there likely to be resistance to replacing the infrastructure, even though the new technology such as H.264 is much better. The method and system of the invention provides a way to use the new technology “where it counts,” keeping the existing infrastructure where it makes sense to do so. Thus, the invention provides a novel solution to a new need.
Note also that one aspect of the invention is to use transcoders. Transcoding between one compression standard and another is known. See for example, P. N. Tudor and O. H. Werner, “REAL-TIME TRANSCODING OF MPEG-2 VIDEO BIT STREAMS,” Proceedings of the 1997 International Broadcasting Convention (IBC 97), held in Amsterdam Netherlands, published by IEE, pages 286-301, 1997. However, because infrastructure for transporting compressed streams is only now becoming widespread, the problem solved by the invention is new, and thus, so is the solution: the use of transcoding in this novel manner to solve this new problem.